A tailor judging a shirt rarely starts with the front. He turns it inside out, runs a thumb along the side seam and looks at how the sleeve meets the body. The outside of a shirt shows its design; the inside shows how it was made. Linen shirt seams in particular repay that attention, because linen is a cloth that frays readily at a cut edge, and the way those edges are handled says a great deal about the care taken over the whole garment.

The first thing to look for is whether the raw edges of the cloth are enclosed or exposed. On many shirts, the edges inside the side seams and armholes are finished with an overlock stitch, a looping thread that wraps the edge to stop it fraying. It is practical and quick, and it works, but it leaves a ridge of thread on the inside that can be felt against the skin and that wears with washing. An enclosed seam hides the raw edge entirely within folded cloth.

Two enclosed seams are traditional in good shirtmaking. The flat-felled seam folds one edge over the other and stitches it down twice, leaving two parallel rows of stitching on the outside and a flat, clean finish inside; it is strong and lies smoothly, which is why it is classic on side seams and sleeves. The French seam sews the edges together, trims them and folds them inside a second, narrow seam, a finish suited to light cloth. In linen, either one keeps the fraying edge locked away and the inside as smooth as the outside.

Stitch density is the next marker. Count the stitches along an inch of seam: finer shirts tend to use more, shorter stitches, which lie flat and hold the cloth evenly. Too many, though, can make linen pucker, because the yarn is relatively thick and the needle holes crowd one another. Good linen shirts find a balance that looks neat without strain. A slight ripple along a seam after the first wash is normal for linen, where thread and cloth relax at slightly different rates, and it settles with wear; tight, gathered puckering that never relaxes points to poor tension.

Beyond the seams, a few other details are worth checking. The collar should roll softly and sit symmetrically, with both points the same length; in linen, a soft collar usually suits the cloth better than a stiffly fused one, and the linen shirt collar guide sets out the styles. The yoke across the shoulders, sometimes cut in two pieces to follow the slope of each shoulder, should lie flat. Buttonholes should be densely stitched with no loose threads, and buttons sewn on firmly with a little room beneath them so they close easily. The linen shirt button guide covers natural buttons in detail.

Hems and small reinforcements complete the reading. A narrow, evenly turned hem along the curved shirt tail suggests patience; a wide, wavering one suggests speed. Some fine shirts add a small triangle of cloth at the base of each side seam, a gusset, which strengthens the point where the seam meets the hem. None of these details is visible across a room, but together they explain why one shirt still looks right after five summers and another loses its shape after five washes.

Handwork changes the picture further. A shirt sewn by hand, piece by piece, is made more slowly and with more attention at every join, which is the point of what it means when a shirt is truly handmade. The PP shirts in the PP linen shirts collection are handmade in the house's Dubai atelier, closed with natural seashell or walnut buttons, and they invite exactly this kind of inspection. Small irregularities in the cloth itself, the slubs of the flax yarn, are not faults but part of the material.

Anyone can apply this test in a boutique or at home. Turn the shirt inside out, look at the side seam and the armhole, count a few stitches and feel the collar. A few minutes with the inside of a shirt tell more about its quality than the label on its collar or the price on its tag.

Read more: How to Identify Premium Linen  ·  Linen Slubs